Method of manufacturing semiconductor image sensor

ABSTRACT

A method of manufacturing a semiconductor device includes disposing a plurality of a first type of light sensing units on a substrate; and disposing a plurality of a second type of light sensing units arranged on the substrate. Each of the first type of light sensing units is operable to receive less radiation than each of the second type of light sensing units. At least one of the second type of light sensing units is adjacent to a portion of at least one of the first type of light sensing units. The method includes disposing a first isolation structure between one of the first type of light sensing units and one of the second type of light sensing units; and disposing a second isolation structure between the adjacent first type of light sensing units. The method includes disposing a reflective layer above the first type of light sensing units.

PRIORITY CLAIM

This application is a divisional of U.S. application Ser. No. 17/220,212, filed Apr. 1, 2021, which claims the priority of U.S. Provisional Application No. 63/053,094, filed Jul. 17, 2020, which are incorporated herein by reference in their entireties.

BACKGROUND

Semiconductor image sensors are used for sensing light. The semiconductor image sensors utilize an array of pixels in a substrate, including photodiodes and transistors that can absorb radiation projected toward the substrate and convert the sensed radiation into electrical signals.

A performance of a semiconductor image sensor depends on, among other things, its quantum efficiency and optical crosstalk. The quantum efficiency of an image sensor indicates a number of electrons generated per number of incident photons in the image sensor. The optical crosstalk occurs when some photons incident upon a pixel are absorbed by another pixel.

Therefore, while existing semiconductor structures of image sensors and conventional methods of manufacturing image sensors have been generally adequate for their intended purposes, they have not been entirely satisfactory in every aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1(a) illustrates a top view of a semiconductor device according to some embodiments of the present disclosure. FIG. 1(b) illustrates a cross-sectional view taken along line A-A′ of the semiconductor device in FIG. 1(a).

FIG. 2(a) illustrates a top view of a semiconductor device according to some embodiments of the present disclosure. FIG. 2(b) illustrates a cross-sectional view taken along line B-B′ of the semiconductor device in FIG. 2(a).

FIG. 3(a) illustrates a top view of a semiconductor device according to some embodiments of the present disclosure. FIG. 3(b) illustrates a cross-sectional view taken along line C-C′ of the semiconductor device in FIG. 3(a).

FIG. 4(a) illustrates a top view of a semiconductor device according to some embodiments of the present disclosure. FIG. 4(b) illustrates a cross-sectional view taken along line D-D′ of the semiconductor device in FIG. 4(a).

FIG. 5 illustrates a cross-sectional view of a semiconductor device according to some embodiments of the present disclosure.

FIG. 6 illustrates a cross-sectional view of a semiconductor device according to some embodiments of the present disclosure.

FIG. 7 illustrates a cross-sectional view of a semiconductor device according to some embodiments of the present disclosure.

FIG. 8A, FIG. 8B, FIG. 8C, FIG. 8D, FIG. 8E, FIG. 8F, FIG. 8G, and FIG. 8H illustrate a method of manufacturing a semiconductor device such as the semiconductor device of FIG. 2(a), FIG. 2(b), FIG. 3(a), and FIG. 3(b).

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of elements and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” “on” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

As used herein, the terms such as “first,” “second,” and “third” describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another. The terms such as “first,” “second,” and “third” when used herein do not imply a sequence or order unless clearly indicated by the context.

As used herein, the terms “approximately,” “substantially,” “substantial,” and “about” are used to describe and account for small variations. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs to a close approximation. For example, when used in conjunction with a numerical value, the terms can refer to a range of variation of less than or equal to ±10% of that numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, two numerical values can be deemed to be “substantially” the same or equal if a difference between the values is less than or equal to ±10% of an average of the values, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, “substantially” parallel can refer to a range of angular variation relative to 0° that is less than or equal to ±10°, such as less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3°, less than or equal to ±2°, less than or equal to ±1°, less than or equal to ±0.5°, less than or equal to ±0.1°, or less than or equal to ±0.05°. For example, “substantially” perpendicular can refer to a range of angular variation relative to 90° that is less than or equal to ±10°, such as less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3°, less than or equal to ±2°, less than or equal to ±1°, less than or equal to ±0.5°, less than or equal to ±0.1°, or less than or equal to ±0.05°.

Some embodiments of image sensors use at least two kinds of pixel sensors, classified by the incident radiation, forming a repeating unit arranged in an array. For example, some embodiments of an image sensor include a first pixel sensor for sensing long wavelengths (e.g., infrared (IR) and red light) and a second pixel sensor for sensing short wavelengths (e.g., green and blue light). In addition, in some embodiments, each of the pixel sensors further use at least two kinds of light sensing units, classified by the amount of the incident radiation (or light) to be received. For example, as used herein, a first light sensing unit refers to a light sensing unit that is operable to receive less radiation (or light) compared to a second light sensing unit given a certain period of time.

As the size of an image sensor gets smaller, crosstalk becomes a major concern between neighboring pixel sensors and further the neighboring light sensing units contained in the neighboring pixel sensors. As the surface area for receiving light becomes smaller, the light sensing unit becomes more sensitive to crosstalk because the signal (light directly received by the sensor) is smaller in comparison to the noise (the crosstalk between neighboring pixel sensors). Crosstalk adversely affects the amount of the light that is received by the light sensing unit. Pixel sensor designs which reduce crosstalk provide increased light absorption efficiency, especially beneficial for low levels of incident light.

FIG. 1(a) illustrates a top view of a semiconductor device 101 according to some embodiments of the present disclosure. FIG. 1(b) illustrates a cross-sectional view taken along line A-A′ of the semiconductor device 101 in FIG. 1(a).

The semiconductor device 101 of FIG. 1(a) includes a plurality of first light sensing units 103 a, 103 b and a plurality of second light sensing units 105 a, 105 b, 105 c, 105 d.

The semiconductor device 101 has a first surface 101 a and a second surface 101 b opposite to the first surface 101 a. According to some embodiments, semiconductor device 101 is a bulk semiconductor substrate (e.g., a bulk silicon (Si) substrate), a silicon-on-insulator (SOI) substrate, or a wafer. In some embodiments, the semiconductor device 101 is a wafer.

The first light sensing unit 103 a, 103 b is operable to receive a radiation projected toward the first light sensing unit 103 a, 103 b and convert the radiation to electrical signal. In some embodiments, the first light sensing unit 103 a, 103 b is operable to detect different wavelengths (colors) from an incident light (e.g., blue (B), green (G), and red (R) light). According to some embodiments, the first light sensing unit 103 a, 103 b is a component or a part of a pixel sensor. In some embodiments, the first light sensing unit 103 a, 103 b is arranged in a sub-array in a pixel sensor.

The second light sensing unit 105 a, 105 b, 105 c, 105 d is operable to receive a radiation projected toward the second light sensing unit 105 a, 105 b, 105 c, 105 d and convert the radiation to electrical signal. In some embodiments, the second light sensing unit 105 a, 105 b, 105 c, 105 d is operable to detect different wavelengths (colors) from an incident light (e.g., blue (B), green (G), and red (R) light). As used herein, the second light sensing unit 105 a, 105 b, 105 c, 105 d refers to a light sensing unit that is operable to receive more radiation than a first light sensing unit 103 a, 103 b. In other words, the first light sensing unit 103 a, 103 b refers to a light sensing unit that is operable to receive less radiation than a second light sensing unit 105 a, 105 b, 105 c, 105 d. In some embodiments, the first light sensing unit 103 a, 103 b is operable to receive less radiation by disposing a reflective layer 119 above the first light sensing unit 103 a, 103 b. In some embodiments, the second light sensing unit 105 a, 105 b, 105 c, 105 d is also a component or a part of a pixel sensor. According to some embodiments, the second light sensing unit 105 a, 105 b, 105 c, 105 d is arranged in a sub-array with the first light sensing unit 103 a, 103 b in a pixel sensor.

The first light sensing unit 103 a, 103 b and the second light sensing unit 105 a, 105 b, 105 c, 105 d constitute a pixel sensor. According to some embodiments, a pixel sensor includes at least one first light sensing unit 103 a, 103 b and at least one second light sensing unit 105 a, 105 b, 105 c, 105 d. In some embodiments, the first light sensing unit 103 a, 103 b is disposed adjacent to at least two second light sensing units 105 a, 105 b, 105 c, 105 d. In some embodiments, the first light sensing unit 103 a, 103 b is disposed adjacent to two, three, four, five, six, seven, or eight second light sensing units 105 a, 105 b, 105 c, 105 d. In some embodiments, the first light sensing unit 103 a, 103 b is surrounded by the second light sensing unit 105 a, 105 b, 105 c, 105 d around a periphery of the first light sensing unit 103 a, 103 b. In some embodiments, the second light sensing units 105 a, 105 b, 105 c, 105 d is a circular region surrounded by the first light sensing units 103 a, 103 b. According to some embodiments, the first light sensing unit 103 a, 103 b is surrounded by at least two second light sensing units 105 a, 105 b, 105 c, 105 d in a pixel sensor. In some embodiments, a first light sensing unit 103 a, 103 b is surrounded by three second light sensing units 105 a, 105 b, 105 c, which constitute a repeating pixel sensor unit. In some embodiments, a repeating pixel sensor unit includes a first light sensing unit 103 a, 103 b surrounded by four second light sensing units 105 a, 105 b, 105 c, 105 d.

According to some embodiments, a pixel sensor composed of the first light sensing unit 103 a and the second light sensing units 105 a, 105 b, 105 c, 105 d is one of a blue light sensor, a green light sensor, and a red light sensor.

According to some embodiments, a first isolation structure 111 a, 111 b, 111 c is further disposed between the first light sensing unit 103 a, 103 b and the neighboring second light sensing unit 105 a, 105 b so the light projected toward to the second light sensing unit 105 a, 105 b is blocked and does not reach the first light sensing unit 103 a, 103 b. As a result, crosstalk interference from the neighboring second light sensing unit 105 a, 105 b to the first light sensing unit 103 a, 103 b is reduced. According to some embodiments, the first isolation structure 111 a, 111 b, 111 c has a substantially rectangular shape, a trapezoidal shape, an elongated elliptical shape, or any other suitable shape. In some embodiments, the first isolation structure 111 a, 111 b, 111 c includes a liner 107 a, 107 b and an insulating structure 109 a, 109 b.

The liner 107 a, 107 b is disposed in conformity with a trench 108 a, 108 b disposed adjacent to the first surface 101 a of the semiconductor device 101.

In some embodiments, the liner 107 a, 107 b includes a low-refractive index (low-n) material which has a refractive index (n) less than a color filter operable for the first light sensing unit 103 a, a high-k (high dielectric constant) material, or a combination thereof. In some embodiments, the low-n material includes, for example, SiO₂, HfO₂, or a combination thereof. In some embodiments, the high-k material includes, for example, HfO₂, Al₂O₃, TiO₂, HfZrO, Ta₂O₃, Ta₂O₅, HfSiO₄, ZrO₂, ZrSiO₂, Ln₂O₃, or a combination thereof.

The insulating structure 109 a, 109 b is disposed adjacent to the liner 107 a, 107 b. In some embodiments, the insulating structure 109 a, 109 b is disposed on the liner 107 a, 107 b. In some embodiments, the insulating structure 109 a, 109 b includes a low-n material, which has a refractive index (n) less than a color filter operable for the first light sensing unit 103 a. In some embodiments, the low-n material includes, for example, SiO₂, HfO₂, or a combination thereof. In some embodiments, the insulating structure 109 a, 109 b also includes a low-k material (e.g., a glass material composed of fluorine, silicon, and oxygen), an oxide layer, and a reflective material to prevent the radiation projected toward one side of the insulation structure 109 a, 109 b from entering another side of the insulation structure 109 a, 109 b to further reduce the crosstalk between the first light sensing unit 103 a, 103 b and the second light sensing unit 105 a, 105 b.

A logic device 123 a, 123 b, such as a transistor, is further disposed in the semiconductor device 101 and operable to enable readout of the first light sensing unit 103 a, 103 b, the second light sensing unit 105 a, 105 b, 105 c, 105 d, or both. In some embodiments, the logic device 123 a, 123 b is disposed adjacent to the first light sensing unit 103 a, 103 b, the second light sensing unit 105 a, 105 b, 105 c, 105 d, or both. In some embodiments, the logic device 123 a, 123 b is disposed adjacent to a third surface 101 c opposite to the first surface 101 a of the semiconductor device 101 and close to the back end of the first light sensing unit 103 a, 103 b and the second light sensing unit 105 a, 105 b, 105 c, 105 d.

According to some embodiments, the circuit stack 129 is further disposed adjacent to the logic device 123 a, 123 b. In some embodiments, circuit stack 129 is disposed adjacent to the second surface 101 b of the semiconductor device 101. In some embodiments, circuit stack 129 is a back-end-of-line (BEOL) metallization stack. In some embodiments, circuit stack 129 electrically connects to the logic device 123 a, 123 b through at least one conductive via, at least one conductive contact, or a combination thereof. In some embodiments, circuit stack 129 includes at least one metal layer 127 and at least one dielectric layer 125.

The metal layer 127 is disposed in the dielectric layer 125. In some embodiments, the metal layer 127 includes, for example, copper, tungsten, aluminum, other metals, or a metal alloy thereof.

According to some embodiments, dielectric layer 125 includes a low-k material (e.g., a dielectric material having a dielectric constant less than 3.9).

FIG. 2(a) illustrates a top view of a semiconductor device 201 according to some embodiments of the present disclosure. The semiconductor device 201 illustrated in FIG. 2(a) is similar to that illustrated in FIG. 1(a) with a difference including that at least a portion of a first light sensing units 203 a is adjacent to at least one first light sensing unit 203 b, 203 c, 203 d. FIG. 2(b) illustrates a cross-sectional view taken along line B-B′ of the semiconductor device 201 in FIG. 2(a).

Unlike the semiconductor device 101 illustrated in FIG. 1(a) and FIG. 1(b), the semiconductor device 201 illustrated in FIG. 2(a) and FIG. 2(b) includes at least one first light sensing unit 203 a disposed adjacent to at least one first light sensing unit 203 b, 203 c, 203 d. In some embodiments, at least one side surface of the first light sensing unit 203 a is disposed adjacent to at least one first light sensing unit 203 b, 203 c, 203 d. In some embodiments, at least two side surfaces of the first light sensing unit 203 a is disposed adjacent to at least one first light sensing unit 203 b, 203 c, 203 d. In some embodiments, a first instance of a first light sensing unit 203 a may be adjoined at a first side by a second instance of the first light sensing unit 203 b, and at a second side adjacent to the first side by a third instance of the first light sensing unit 203 d. In some embodiments, at least a portion of the first light sensing unit 203 a is surrounded by at least one first light sensing unit 203 b, 203 c, 203 d. In some embodiments, at least a portion of the first light sensing unit 203 a is surrounded by at least two first light sensing units 203 b, 203 c. In some embodiments, at least a portion of the first light sensing unit 203 a is surrounded by at least three first light sensing units 203 b, 203 c, 203 d.

At least a portion of the first light sensing unit 203 a is surrounded by at least a portion of another first light sensing unit 203 b, 203 c, 203 d and at least a portion of the first light sensing unit 203 a is surrounded by at least a portion of a second light sensing unit 205 a. In some embodiments, at least a portion of the first light sensing unit 203 a is surrounded by at least a portion of another first light sensing unit 203 b, 203 c, 203 d and the rest portions of the first light sensing unit 203 a is surrounded by at least a portion of a second light sensing unit 205 a.

In some embodiments, the first light sensing unit 203 a and the second light sensing unit 205 a constitute a pixel sensor. According to some embodiments, a pixel sensor includes at least one first light sensing unit 203 a and at least one second light sensing unit 205 a. In some embodiments, the first light sensing unit 203 a is adjacent to at least one second light sensing unit 205 a. In some embodiments, the first light sensing unit 203 a is disposed adjacent to one, two, three, four, or five second light sensing units 205 a, 205 b, 205 c. In some embodiments, the first light sensing unit 203 a is surrounded by the second light sensing unit 205 a, 205 b, 205 c partially. In some embodiments, first light sensing unit 203 a is surrounded by at least one second light sensing unit 205 a in a pixel sensor. In some embodiments, a repeating pixel sensor unit includes a first light sensing unit 203 a surrounded by a second light sensing unit 205 a. In some embodiments, the first light sensing unit 203 a is disposed adjacent to a corner of a pixel sensor. In some embodiments, the first light sensing unit 203 a is located at a corner of a pixel sensor. In some embodiments, a projection area of the first light sensing unit 203 a, 203 b to the projection area of the second light sensing unit 205 a, 205 b is about 1:3.

In some embodiments, a first light sensing unit 203 a is surrounded by one second light sensing units 205 a of the same pixel sensor and by another second light sensing unit 205 b, 205 c of another pixel sensor. In some embodiments, the portion of the first light sensing unit 203 a surrounded by the second light sensing units 205 a of the same pixel sensor is not greater than the portion of the first light sensing unit 203 a surrounded by a first light sensing unit 203 b, 203 c, 203 d.

By disposing at least a portion of a first light sensing units 203 a adjacent to at least one first light sensing unit 203 b, the crosstalk occurred due to the reflection or refraction of the light from the neighboring second light sensing unit 205 a to the first light sensing units 203 a is reduced as the area of the second light sensing unit 205 b surrounding the first light sensing unit 203 a is reduced. As a result, since the light interference (e.g., crosstalk) from the neighboring second light sensing unit 205 a, 205 b is reduced, the light sensitivity of the first light sensing units 203 a, 203 b increases.

Referring to FIG. 2(b), in some embodiments where a first light sensing unit 203 a is disposed adjacent to another first light sensing unit 203 b, the reflective layer 219 extends from a projection area of the first light sensing unit 203 a to a projection area of the first light sensing unit 203 b.

FIG. 3(a) illustrates a top view of a semiconductor device 301 according to some embodiments of the present disclosure. The semiconductor device 301 illustrated in FIG. 3(a) is similar to that illustrated in FIG. 2(a) with a difference including that a side surface 303 e of the first light sensing unit 303 a is curved by which the portion of the first light sensing unit 303 a surrounded by the second light sensing units 305 a of the same pixel sensor may be further reduced compared to that illustrated in FIG. 2(a). In some embodiments, the portion of the first light sensing unit 303 a surrounded by the second light sensing units 305 a of the same pixel sensor is smaller than the portion of the first light sensing unit 303 a surrounded by a first light sensing unit 303 b, 303 c, 303 d. As a result, since the portion of the first light sensing unit 303 a surrounded by the second light sensing units 305 a of the same pixel sensor may be further reduced, the crosstalk interference mentioned above is further reduced compared to that illustrated in FIG. 2(a).

FIG. 3(b) illustrates a cross-sectional view taken along line C-C′ of the semiconductor device 301 in FIG. 3(a). The structure of the semiconductor device 301 illustrated in FIG. 3(b) is similar to that illustrated in FIG. 2(b), which are not further described for brevity.

FIG. 4(a) illustrates a top view of a semiconductor device 401 according to some embodiments of the present disclosure. The semiconductor device 401 illustrated in FIG. 4(a) is similar to that illustrated in FIG. 2(a) with a difference including that an third light sensing unit 431 a, 431 b is disposed between the first light sensing unit 403 a, 403 b and the second light sensing unit 405 a, 405 b. FIG. 4(b) illustrates a cross-sectional view taken along line D-D′ of the semiconductor device 401 in FIG. 4(a).

In some embodiments, the third light sensing unit 431 a, 431 b is different from the first light sensing unit 403 a, 403 b and the second light sensing unit 405 a, 405 b so the third light sensing unit 431 a, 431 b could be distinguished from the first light sensing unit 403 a, 403 b and not cause a crosstalk as the second light sensing unit 405 a, 405 b does. In some embodiments, the third light sensing unit 431 a, 431 b is operable to receive a radiation projected toward the third light sensing unit 431 a, 431 b and convert the radiation to electrical signal. In some embodiments, the third light sensing unit 431 a, 431 b is operable to receive less radiation projected toward it than the first light sensing unit 403 a, 403 b, the second light sensing unit 405 a, 405 b, or both and convert the radiation to electrical signal. As a result, since the third light sensing unit 431 a, 431 b may receive less radiation projected toward it than the second light sensing unit 405 a, 405 b, it may cause less crosstalk than the second light sensing unit 405 a, 405 b does, which further reduces the crosstalk interference toward the first light sensing unit 403 a, 403 b compared to a second light sensing unit 405 a, 405 b.

In addition, since disposing the third light sensing unit 431 a, 431 b between the first light sensing unit 403 a, 403 b and the second light sensing unit 405 a, 405 b may increase the distance between them and make the crosstalk source of the second light sensing unit 405 a, 405 b to be away from the first light sensing unit 403 a, 403 b, less crosstalk may reach the first light sensing unit 403 a, 403 b, which further improves the sensitivity of the first light sensing unit 403 a, 403 b.

FIG. 5 illustrates a cross-sectional view of a semiconductor device 501 according to some embodiments of the present disclosure. The semiconductor device 501 illustrated in FIG. 5 is similar to that illustrated in FIG. 1(a), FIG. 2(a), FIG. 3(a), and FIG. 4(a) with a difference including that the first isolation structure 511 b has a larger projection area compared to a regular design.

In some embodiments, such as those illustrated in FIG. 5 where the first isolation structure 511 b is disposed separating the first light sensing unit 503 a from the second light sensing unit 505 b, a projection area of the first isolation structure 511 b is enlarged compared to a regular design so less crosstalk transmits through it and reaches the first light sensing unit 503 a, 503 b. As a result, the crosstalk interference from the neighboring second light sensing unit 505 b is reduced.

In some embodiments, such as those illustrated in FIG. 5 where a first isolation structure 511 b is disposed separating the first light sensing unit 503 a from the second light sensing unit 505 b and a second isolation structure 511 a is disposed separating the first light sensing unit 503 a from another first light sensing unit 503 b, the crosstalk interference from the neighboring second light sensing unit 505 b is reduced by disposing the first isolation structure 511 b having a larger projection area than the second isolation structure 511 a.

In some embodiments, the first isolation structure 511 b includes a liner 507 b and an insulating structure 509 b. In some embodiments, the second isolation structure 511 a includes a liner 507 a and an insulating structure 509 a. The liners 507 b, 507 a and the insulation structures 509 b, 509 a are similar to those described above and are not further described for brevity.

FIG. 6 illustrates a cross-sectional view of a semiconductor device 601 according to some embodiments of the present disclosure. The semiconductor device 601 illustrated in FIG. 6 is similar to that illustrated in FIG. 1(a), FIG. 2(a), FIG. 3(a), and FIG. 4(a) with a difference including that the reflective layer 619 extends from a projection area of the first light sensing unit 603 a to a projection area of a neighboring second light sensing unit 605 b.

By disposing the reflective layer 619 extending from a projection area of the first light sensing unit 603 a to a projection area of a neighboring second light sensing unit 605 b, the reflective layer 619 reduces the light projected toward the second light sensing unit 605 b and crosstalk generated from the first light sensing unit 603 a. Nevertheless, it should be noted that embodiments of the extension of the reflective layer 619 are designed that the reduction of the light toward the second light sensing unit 605 b by the reflective layer 619 does not affect the intended purpose of the second light sensing unit 605 b as receiving more radiation than a first light sensing unit 603 a.

FIG. 7 illustrates a cross-sectional view of a semiconductor device 701 according to some embodiments of the present disclosure. The semiconductor device 701 illustrated in FIG. 7 is similar to that illustrated in FIG. 1(a), FIG. 2(a), FIG. 3(a), and FIG. 4(a) with a difference including that a first surface 733 of a second light sensing unit 705 b has roughness.

The second light sensing unit 705 b has a first surface 733 facing the reflective layer 719 and a second surface 701 b opposite to the first surface 733.

By disposing the first surface 733 of the second light sensing unit 705 b as having roughness compared to the first surface 101 a of the semiconductor device 101, less light is transmitted through the semiconductor device 701 to reach the second light sensing unit 705 b because some light is refracted or reflected by the roughed first surface 733 of the second light sensing unit 705 b. As a result, since less light reaches the second light sensing unit 705 b because of the roughed first surface 733, less crosstalk interference is generated toward the neighboring first light sensing unit 703 a. Therefore, the sensitivity of the neighboring first light sensing unit 703 a increases. It should be noted that the roughness of the first surface 733 of the second light sensing unit 705 b is so designed that the reduction of the light toward the second light sensing unit 705 b by the roughness of the first surface 733 does not affect the intended purpose of the second light sensing unit 705 b as receiving more radiation than a first light sensing unit 703 a.

FIGS. 8A-8H illustrate a method of manufacturing a semiconductor device such as the semiconductor device of FIG. 2(a), FIG. 2(b), FIG. 3(a), and FIG. 3(b).

Referring to FIG. 8A, a substrate 801 is provided or received. The substrate 801 has a first surface 801 a and a second surface 801 b opposite to the first surface 801 a. In some embodiments, the substrate 801 is a bulk semiconductor substrate (e.g., a bulk silicon (Si) substrate), a silicon-on-insulator (SOI) substrate, or a wafer. In some embodiments, the substrate 801 is a wafer.

The substrate 801 includes a plurality of first light sensing units 803 a, 803 b and a plurality of second light sensing units 805 a, 805 b arranged in a sub-array adjacent to the first surface 801 a of the substrate 801. The first light sensing units 803 a, 803 b and the second light sensing units 805 a, 805 b are so disposed that at least a portion of the first light sensing unit 803 a is adjacent to at least one first light sensing unit 803 b. In some embodiments, the first light sensing units 803 a, 803 b are different from the second light sensing units 805 a, 805 b in that a surface of the second light sensing units 805 a, 805 b is roughened.

A logic device 823 a, 823 b, such as a transistor, may be further disposed to a third surface 801 c opposite to the first surface 801 a of the substrate 801. The logic device 823 a, 823 b is operable to enable readout of the first light sensing unit 803 a, 803 b, the second light sensing unit 805 a, 805 b, or both. In some embodiments, the logic device 823 a, 823 b is disposed adjacent to the first light sensing unit 803 a, 803 b, the second light sensing unit 805 a, 805 b, or both. In some embodiments, the logic device 823 a, 823 b is disposed adjacent to a third surface 801 c opposite to the first surface 801 a of the substrate 801 and close to the back end of the first light sensing unit 803 a, 803 b and the second light sensing unit 805 a, 805 b.

A circuit stack 829 may be further disposed adjacent to the logic device 823 a, 823 b. The circuit stack 829 may be disposed adjacent to the second surface 801 b of the substrate 801. In some embodiments, the circuit stack 829 is a back-end-of-line (BEOL) metallization stack.

According to some embodiments, circuit stack 829 electrically connects to the logic device 823 a, 823 b through at least one conductive via, at least one conductive contact, or a combination thereof. In some embodiments, the circuit stack 829 includes at least one metal layer 827 and at least one dielectric layer 825.

Still referring to FIG. 8A, a trench 808 c, 808 b, 808 a, may be disposed between the first light sensing unit 803 a and the second light sensing unit 805 a, the first light sensing unit 803 a and the first light sensing unit 803 b, and the first light sensing unit 803 b and the second light sensing unit 805 b. In some embodiments, trenches 808 c, 808 b, 808 a have a substantially rectangular shape, a trapezoidal shape, an elongated elliptical shape, or any other suitable shape.

In some embodiments, trenches 808 c, 808 b, 808 a are formed by an etching technology, a drilling technology (e.g., a mechanical or laser drilling technology), or any suitable technologies applied from the first surface 801 a of the substrate 801 toward the second surface 801 b of the substrate 801.

Referring to FIG. 8B, a liner 807 is disposed adjacent to the first surface 801 a of the substrate 801. The liner 807 is disposed in conformity with the shape of the trench 808 c, 808 b, 808 a of the substrate 801. In some embodiments, the liner 807 is formed by an atomic layer deposition (ALD) technology, a chemical vapor deposition (CVD) technology, or any suitable technologies.

Referring to FIG. 8C, an insulating structure 809 a, 809 b, 809 c is disposed adjacent to the liner 807. In some embodiments, the insulating structure 809 a, 809 b, 809 c fills the trench 808 c, 808 b, 808 a of the substrate 801. In some embodiments, the insulating structures 809 a, 809 b, 809 c are disposed by an atomic layer deposition (ALD) technology, a chemical vapor deposition (CVD) technology, or any suitable technologies.

Referring to FIG. 8D, a first dielectric layer 813 is disposed adjacent to the liner 807. In some embodiments, the first dielectric layer 813 is disposed on the liner 807 and the insulating structure 809 a, 809 b, 809 c. In some embodiments, the first dielectric layer 813 is disposed by an atomic layer deposition (ALD) technology, a chemical vapor deposition (CVD) technology, or any suitable technologies.

Referring to FIG. 8E, a metal layer 815 a, 815 b, 815 c is disposed adjacent to the first dielectric layer 813. In some embodiments, the metal layers 815 a, 815 b, 815 c are disposed corresponding to the portions of the first isolation structure 811 a, 811 b, 811 c. In some embodiments, the metal layers 815 a, 815 b, 815 c are formed by a technology selected from a plating technology, a photolithography technology, a polishing technology, and an etching technology.

Referring to FIG. 8F, a second dielectric layer 817 is disposed adjacent to the first dielectric layer 813. In some embodiments, the second dielectric layer 817 is disposed on the metal layer 815 a, 815 b, 815 c and the first dielectric layer 813. In some embodiments, the second dielectric layer 817 is disposed by an atomic layer deposition (ALD) technology, a chemical vapor deposition (CVD) technology, or any suitable technologies.

Referring to FIG. 8G, a reflective layer 819 is disposed adjacent to the second dielectric layer 817. The reflective layer 819 is disposed at a position corresponding to the first light sensing units 803 a, 803 b, which defines the area of the first light sensing units 803 a, 803 b. In some embodiments, the reflective layer 819 is disposed by a technology selected from a plating technology, a photolithography technology, a polishing technology, and an etching technology.

Referring to FIG. 8H, a third dielectric layer 821 is disposed adjacent to the second dielectric layer 817. In some embodiments, the third dielectric layer 821 is disposed over the reflective layer 819 and the second dielectric layer 817. In some embodiments, the third dielectric layer 821 is disposed by an atomic layer deposition (ALD) technology, a chemical vapor deposition (CVD) technology, or any suitable technologies. Subsequently, a semiconductor device, such as the one illustrated in FIG. 2(b) and FIG. 3(b) are obtained.

In some embodiments, a singularizing process is further performed on the semiconductor device obtained from the process mentioned above to obtain an image sensor including at least one pixel sensor including a first light sensing unit 803 a and a second light sensing unit 805 a arranged in a sub-array with the first light sensing unit 803 a, where at least a portion of the first light sensing unit 803 a is adjacent to at least one first light sensing unit 803 b of another pixel sensor.

An aspect of this description relates to a method of manufacturing a semiconductor device. The method includes disposing a plurality of a first type of light sensing units on a substrate. The method further includes disposing a plurality of a second type of light sensing units arranged on the substrate, wherein each of the plurality of the first type of light sensing units is operable to receive less radiation compared to each of the plurality of the second type of light sensing units, and disposing the plurality of the second type of light sensing units comprises disposing at least one of the plurality of the second type of light sensing units adjacent to a portion of at least one of the plurality of the first type of light sensing units. The method further includes disposing a first isolation structure between one of the plurality of the first type of light sensing units and one of the plurality of the second type of light sensing units. The method further includes disposing a second isolation structure between the adjacent first type of light sensing units of the plurality of the first type of light sensing units. The method further includes disposing a reflective layer above the plurality of the first type of light sensing units. In some embodiments, disposing the first isolation structure includes disposing the first isolation structure having a larger projection area than the second isolation structure. In some embodiments, disposing the reflective layer includes disposing the reflective layer extending from a projection area of the plurality of the first type of light sensing units to a projection area of the plurality of the second type of light sensing units. In some embodiments, the method further includes roughening a surface of at least one of the plurality of the second type of light sensing units. In some embodiments, the method further includes disposing a third type of light sensing unit between at least one of the plurality of the first type of light sensing units and at least one of the plurality of the second type of light sensing units, wherein the third type of light sensing unit is operable to receive less radiation than each of the plurality of the first type of light sensing units or each of the plurality of the second type of light sensing units.

An aspect of this description relates to a method of manufacturing a semiconductor device. The method includes forming a first plurality of light sensing elements on a substrate. The method further includes forming a second plurality of light sensing elements on the substrate, wherein the second plurality of light sensing elements surrounds the first plurality of light sensing elements, and each of the second plurality of light sensing elements is configured to receive a higher intensity of light than each of the first plurality of light sensing elements. The method further includes forming a first plurality of isolation structures, wherein each of the first plurality of isolation structures is between a light sensing element of the second plurality of light sensing elements and a corresponding light sensing element of the first plurality of light sensing elements. The method further includes forming a second plurality of isolation structures, wherein each of the second plurality of isolation structures is between adjacent light sensing elements of the first plurality of light sensing elements. The method further includes forming a plurality of metal structures over the first plurality of isolation structures and the second plurality of isolation structures, wherein each of the plurality of metal structures is aligned with a corresponding light sensing element of the first plurality of light sensing elements or a corresponding light sensing element of the second plurality of light sensing elements. The method further includes forming a reflective layer over at least a portion of a first metal structure of the plurality of metal structures, wherein the reflective layer overlaps a first light sensing element of the first plurality of light sensing elements. In some embodiments, the method further includes forming a third plurality of light sensing elements on the substrate, wherein the third plurality of light sensing elements is between the first plurality of light sensing elements and the second plurality of light sensing elements. In some embodiments, forming the first plurality of light sensing elements includes forming the first plurality of light sensing element having a curved surface. In some embodiments, forming the reflective layer includes forming the reflective layer over an entirety of the first metal structure. In some embodiments, forming the reflective layer includes forming the reflective layer over the first metal structure, and the first metal structure is over a first isolation structure of the first plurality of isolation structures. In some embodiments, forming the reflective layer includes forming the reflective layer over the first metal structure, and the first metal structure is over a first isolation structure of the second plurality of isolation structures. In some embodiments, forming the reflective layer comprises forming the reflective layer overlapping the first light sensing element and a second light sensing element of the first plurality of light sensing elements. In some embodiments, the method further includes roughening a surface of at least one of the plurality of second light sensing elements. In some embodiments, forming the reflective layer includes forming the reflective layer partially overlapping a first light sensing element of the second plurality of light sensing elements. In some embodiments, forming the first plurality of isolation structures includes forming the first plurality of isolation structures simultaneously with forming the second plurality of isolation structures.

An aspect of this description relates to a method of manufacturing a semiconductor device. The method includes forming a first light sensing on a substrate, wherein the first light sensing element is configured to receive a first amount of light. The method further includes forming a second light sensing element on the substrate, wherein the second light sensing element is configured to receive the first amount of light. The method further includes forming a third light sensing element on the substrate, wherein the third light sensing element is configured to receive a second amount of light different from the first amount of light. The method further includes forming a first isolation structure between the first light sensing element and the second light sensing element. The method further includes forming a second isolation structure between the second light sensing element and the third light sensing element. The method further includes roughening a surface of the third light sensing element. The method further includes forming a dielectric layer over the first light sensing element, the second light sensing element, and the third light sensing element, wherein the roughened surface of the third light sensing element is proximate the dielectric layer. In some embodiments, the method further includes forming a first metal structure over the dielectric layer, wherein the first metal structure is aligned with the first isolation structure; and forming a second metal structure over the dielectric layer, wherein the second metal structure is aligned with the second isolation structure. In some embodiments, the method further includes forming a reflective layer over the dielectric layer, wherein the reflective layer overlaps the second light sensing element. In some embodiments, forming the reflective layer includes forming the reflective layer overlapping the first metal structure and the first light sensing element. In some embodiments, forming the reflective layer includes forming the reflective layer partially overlapping the third light sensing element.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

What is claimed is:
 1. A method of manufacturing a semiconductor device, comprising: disposing a plurality of a first type of light sensing units on a substrate; disposing a plurality of a second type of light sensing units arranged on the substrate, wherein each of the plurality of the first type of light sensing units is operable to receive less radiation compared to each of the plurality of the second type of light sensing units, and disposing the plurality of the second type of light sensing units comprises disposing at least one of the plurality of the second type of light sensing units adjacent to a portion of at least one of the plurality of the first type of light sensing units; disposing a first isolation structure between one of the plurality of the first type of light sensing units and one of the plurality of the second type of light sensing units; disposing a second isolation structure between the adjacent first type of light sensing units of the plurality of the first type of light sensing units; and disposing a reflective layer above the plurality of the first type of light sensing units.
 2. The method of claim 1, wherein disposing the first isolation structure comprises disposing the first isolation structure having a larger projection area than the second isolation structure.
 3. The method of claim 1, wherein disposing the reflective layer comprises disposing the reflective layer extending from a projection area of the plurality of the first type of light sensing units to a projection area of the plurality of the second type of light sensing units.
 4. The method of claim 1, further comprising roughening a surface of at least one of the plurality of the second type of light sensing units.
 5. The method of claim 1, further comprising disposing a third type of light sensing unit between at least one of the plurality of the first type of light sensing units and at least one of the plurality of the second type of light sensing units, wherein the third type of light sensing unit is operable to receive less radiation than each of the plurality of the first type of light sensing units or each of the plurality of the second type of light sensing units.
 6. A method of manufacturing a semiconductor device comprising: forming a first plurality of light sensing elements on a substrate; forming a second plurality of light sensing elements on the substrate, wherein the second plurality of light sensing elements surrounds the first plurality of light sensing elements, and each of the second plurality of light sensing elements is configured to receive a higher intensity of light than each of the first plurality of light sensing elements; forming a first plurality of isolation structures, wherein each of the first plurality of isolation structures is between a light sensing element of the second plurality of light sensing elements and a corresponding light sensing element of the first plurality of light sensing elements; forming a second plurality of isolation structures, wherein each of the second plurality of isolation structures is between adjacent light sensing elements of the first plurality of light sensing elements; forming a plurality of metal structures over the first plurality of isolation structures and the second plurality of isolation structures, wherein each of the plurality of metal structures is aligned with a corresponding light sensing element of the first plurality of light sensing elements or a corresponding light sensing element of the second plurality of light sensing elements; and forming a reflective layer over at least a portion of a first metal structure of the plurality of metal structures, wherein the reflective layer overlaps a first light sensing element of the first plurality of light sensing elements.
 7. The method of claim 6, further comprising forming a third plurality of light sensing elements on the substrate, wherein the third plurality of light sensing elements is between the first plurality of light sensing elements and the second plurality of light sensing elements.
 8. The method of claim 6, wherein forming the first plurality of light sensing elements comprises forming the first plurality of light sensing element having a curved surface.
 9. The method of claim 6, wherein forming the reflective layer comprises forming the reflective layer over an entirety of the first metal structure.
 10. The method of claim 6, wherein forming the reflective layer comprises forming the reflective layer over the first metal structure, and the first metal structure is over a first isolation structure of the first plurality of isolation structures.
 11. The method of claim 6, wherein forming the reflective layer comprises forming the reflective layer over the first metal structure, and the first metal structure is over a first isolation structure of the second plurality of isolation structures.
 12. The method of claim 6, wherein forming the reflective layer comprises forming the reflective layer overlapping the first light sensing element and a second light sensing element of the first plurality of light sensing elements.
 13. The method of claim 6, further comprising roughening a surface of at least one of the plurality of second light sensing elements.
 14. The method of claim 6, wherein forming the reflective layer comprises forming the reflective layer partially overlapping a first light sensing element of the second plurality of light sensing elements.
 15. The method of claim 6, wherein forming the first plurality of isolation structures comprises forming the first plurality of isolation structures simultaneously with forming the second plurality of isolation structures.
 16. A method of manufacturing a semiconductor device comprising: forming a first light sensing on a substrate, wherein the first light sensing element is configured to receive a first amount of light; forming a second light sensing element on the substrate, wherein the second light sensing element is configured to receive the first amount of light; forming a third light sensing element on the substrate, wherein the third light sensing element is configured to receive a second amount of light different from the first amount of light; forming a first isolation structure between the first light sensing element and the second light sensing element; forming a second isolation structure between the second light sensing element and the third light sensing element; roughening a surface of the third light sensing element; forming a dielectric layer over the first light sensing element, the second light sensing element, and the third light sensing element, wherein the roughened surface of the third light sensing element is proximate the dielectric layer.
 17. The method of claim 16, further comprising: forming a first metal structure over the dielectric layer, wherein the first metal structure is aligned with the first isolation structure; and forming a second metal structure over the dielectric layer, wherein the second metal structure is aligned with the second isolation structure.
 18. The method of claim 17, further comprising forming a reflective layer over the dielectric layer, wherein the reflective layer overlaps the second light sensing element.
 19. The method of claim 18, wherein forming the reflective layer comprises forming the reflective layer overlapping the first metal structure and the first light sensing element.
 20. The method of claim 18, wherein forming the reflective layer comprises forming the reflective layer partially overlapping the third light sensing element. 